| タイトル | IC 751: A New Changing Look AGN Discovered by NuSTAR |
| 著者（英） | Brandt, W. N.; Arevalo, P.; Stern, D.; Hailey, C. J.; Treister, E.; Bauer, F. E.; Zhang, W. W.; Markwardt, C. B.; Harrison, F. A.; Boggs, S.; Koss, M.; Craig, W. W.; Christensen, F. E.; Ricci, C.; Ghandi, P. |
| 著者所属（英） | NASA Goddard Space Flight Center |
| 発行日 | 2016-03-10 |
| 言語 | eng |
| 内容記述 | We present results of five Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the type 2 active galactic nucleus (AGN) in IC 751, three of which were performed simultaneously with XMM-Newton or Swift/ X-Ray Telescope. We find that the nuclear X-ray source underwent a clear transition from a Compton-thick (NH approx. = 2 x10(exp 24)/sq cm) to a Compton-thin ( N(sub H) approx. = 4 x10(exp 23)/sq cm) state on timescales of < or approx.3 months, which makes IC 751 the first changing look AGN discovered by NuSTAR. Changes of the line of sight column density at the approx.2 (sigma) level are also found on a timescale of approx. 48 hr (delta N(sub H approx. 10(exp 23)/sq cm). From the lack of spectral variability on timescales of approx.100 ks, we infer that the varying absorber is located beyond the emission-weighted average radius of the broad-line region (BLR), and could therefore be related either to the external part of the BLR or a clumpy molecular torus. By adopting a physical torus X-ray spectral model, we are able to disentangle the column density of the non-varying absorber (N(sub H) approx. 3.8 x10(exp 23)/sq cm) from that of the varying clouds [N(sub H) approx. (1- 150) x 10(exp 22)/sq cm], and to constrain that of the material responsible for the reprocessed X-ray radiation (N(sub H approx. 6 x 10(exp 24)/sq cm).24 -2). We find evidence of significant intrinsic X-ray variability, with the flux varying by a factor of five on timescales of a few months in the 2-10 and 10-50 keV band. |
| NASA分類 | Astrophysics |
| レポートNO | GSFC-E-DAA-TN40644 |
| 権利 | Copyright |
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